linux-kernel - [PATCH AUTOSEL 6.6 20/21] MIPS: reserve exception vector space ONLY ONCE

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Date: Fri,  2 Feb 2024 13:40:07 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Huang Pei <huangpei@...ngson.cn>,
	Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
	Sasha Levin <sashal@...nel.org>,
	rdunlap@...radead.org,
	arnd@...db.de,
	akpm@...ux-foundation.org,
	jiaxun.yang@...goat.com,
	bhelgaas@...gle.com,
	linux-mips@...r.kernel.org
Subject: [PATCH AUTOSEL 6.6 20/21] MIPS: reserve exception vector space ONLY ONCE

From: Huang Pei <huangpei@...ngson.cn>

[ Upstream commit abcabb9e30a1f9a69c76776f8abffc31c377b542 ]

"cpu_probe" is called both by BP and APs, but reserving exception vector
(like 0x0-0x1000) called by "cpu_probe" need once and calling on APs is
too late since memblock is unavailable at that time.

So, reserve exception vector ONLY by BP.

Suggested-by: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Signed-off-by: Huang Pei <huangpei@...ngson.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/mips/kernel/traps.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 246c6a6b0261..5b778995d448 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -2007,7 +2007,13 @@ unsigned long vi_handlers[64];
 
 void reserve_exception_space(phys_addr_t addr, unsigned long size)
 {
-	memblock_reserve(addr, size);
+	/*
+	 * reserve exception space on CPUs other than CPU0
+	 * is too late, since memblock is unavailable when APs
+	 * up
+	 */
+	if (smp_processor_id() == 0)
+		memblock_reserve(addr, size);
 }
 
 void __init *set_except_vector(int n, void *addr)
-- 
2.43.0